Time-specific intraocular pressure curves in Rhesus macaques (Macaca mulatta) with laser-induced ocular hypertension

Objective To detect and categorize time‐specific variations in daytime intraocular pressure (IOP) found in Rhesus monkeys with laser‐induced ocular hypertension. Procedures Ten male monkeys with argon laser‐induced ocular hypertension in one eye were anesthetized with ketamine hydrochloride, and the IOP measured in both eyes at 7 a.m., 7.30 a.m., and then hourly until 1 p.m. with a Tonopen? XL applanation tonometer. Intraocular pressure time profiles for both eyes in each animal were developed. The means ± SD of the IOPs for both eyes were calculated for the whole 6‐h study period, and the values compared statistically. The difference between the lasered eye mean IOP standard deviation and the normal eye mean IOP standard deviation for each animal during the 6‐h follow‐up was also calculated and compared. Results Mean IOP (± SD) in the glaucoma and normal eyes for the 10 animals during the 6‐h study was 32.6 ± 2.5 and 14.9 ± 2.5 mmHg, respectively. The IOP was significantly higher in the experimental eye than in the normal eye (P = 0.0008). The mean IOP in the lasered eye did not significantly change during the study period, whereas a slight but significant increase in IOP of the normal eye over the study period was recorded (P = 0.003). The variance in IOP in the hypertensive eyes was considerably greater than that in the untreated control eyes. From 7 a.m. to 1 p.m. the IOP declined in five eyes and increased in the other five eyes with laser‐induced ocular hypertension. Conclusions The time‐specific IOP variation pattern in the daytime in the laser treated eyes is significantly greater than the variation in the normotensive eyes. This shows that in order to detect statistical differences between IOP variations induced by an IOP‐reducing drug, and the exaggerated spontaneous IOP variations present in the laser‐induced hypertensive eye, sufficient animals should be included in any study. Understanding the time‐specific IOP variation present in a group of monkeys with laser‐induced ocular hypertension is essential prior to using the model for the evaluation of IOP‐reducing drugs.     

The influence of high-nitrogen forages on the voluntary feed intake of sheep

The objective of this research was to examine the effect of high concentrations of nonprotein nitrogen (NPN) on the voluntary food intake of sheep fed high-quality grasses. Wether lambs (n = 6 per treatment) were fed dried switchgrass (Panicum virgatum L.; Exp. 1) or dried tall fescue (Festuca arundinacea Schreb.; Exp. 2). In both experiments, urea was added to the dried forage at 0 (control), 12, or 24 g of N/kg of DM to increase the NPN concentration. Acid detergent fiber concentrations were 305 g/kg of DM in both experiments, although DM digestibility was 663 and 618 g/ kg of DM in Exp. 1 and Exp. 2, respectively. Voluntary feed intake of the control forage was 28.2 and 19.1 g/ kg of BW in Exp. 1 and Exp. 2, respectively, and decreased for the high-urea treatments to 25.2 and 16.2 g/kg of BW in Exp. 1 (P = 0.07) and Exp 2 (P = 0.03), respectively. Total feed N concentrations increased from 29.5 g to 45.7 g of N/kg of DM in Exp. 1 (P < 0.01) and from 28.4 to 55.9 g of N/kg of DM in Exp. 2 (P < 0.01). Nonprotein N concentrations increased from 28.3 to 53.8% of the total N in switchgrass diets (Exp. 1; P < 0.01), and from 26.4 to 64.0% in tall fescue diets (Exp. 2; P < 0.01). Plasma urea concentrations of the lambs increased from 3.1 to 6.6 mM (Exp. 1; P < 0.01) and from 2.9 to 5.8 mM (Exp. 2; P < 0.01) as the amount of urea added to the diets increased. These changes resulted in an increase in plasma osmolality from 298 to 307 mOsm/kg (Exp. 1; P = 0.04), and from 299 to 307 mOsm/kg (Exp. 2; P = 0.06). Increasing feed N and NPN concentrations through the addition of urea caused a significant decrease in the voluntary feed intake of sheep fed tall fescue and switchgrass. These responses showed no significant cause-and-effect relationship between voluntary feed intake, plasma urea concentrations, and plasma osmolality.     

Effect of scrapie incubation on the concentrations of plasma amino acids and L-lactate in infected lambs

Three groups of two weeks old growing lambs differing in PrP genotype were orally inoculated with scrapie and maintained under defined conditions until disease endpoint. Plasma concentrations of free alanine and serine, but not L-lactate increased during the final 6 months of the disease. At the same time, plasma concentrations of several essential and non-essential free amino acids decreased linearly, indicating reduced feed intake and are consistent with, but occurring before establishment, of cachexia. These observations are consistent with those reported previously from studies on cattle infected with BSE and with the hypothesis that scrapie may effect peripheral tissue metabolism.     

Normal ranges and temporal variation in plasma concentrations of L-lactate and free amino acids in adult sheep

To determine baseline variation in blood plasma concentrations of free amino acids and l-lactate, samples were collected at a single time point from nine flocks of different breeds of ewes at a common physiological stage and monthly from one flock of crossbred mule ewes over a 12 month period. Significant differences were detected between time points in the concentrations of all plasma metabolites. With few exceptions prion protein genotype had no significant effect on the plasma metabolite concentrations measured.     

Leukemia inhibitory factor protein and receptors are expressed in the bovine adrenal cortex and increase cortisol and decrease adrenal androgen release

The release of adrenal steroids during acute stress is primarily regulated by adrenocorticotropic hormone (ACTH). In contrast, during chronic inflammatory stress additional factors are involved in regulating adrenal function. Leukemia inhibitory factor (LIF) is a pleiotropic cytokine that increases ACTH release from the pituitary. In addition, LIF and LIF receptors (LIFR) are expressed in the human adrenal cortex and the human adrenocortical tumor cell line H295R. Furthermore, LIF increases basal and ACTH-stimulated cortisol release from H295R cells. However, the expression of LIF and LIFR in non-human adrenal glands and the effects of LIF on the release of cortisol from adrenal cells of non-human species have not been determined. Furthermore, the effects of LIF on adrenal androgen release from all species are unknown. In this study, immunohistochemistry, Western blots, RT-PCR, and nucleotide sequencing was utilized to demonstrate that LIF and its receptor are expressed throughout the bovine adrenal cortex. Although LIF did not modify basal cortisol release from dispersed cells isolated from the bovine adrenal zona fasciculate, this cytokine increased ACTH-stimulated release of cortisol from these cells in a manner dependent on the LIF concentration and exposure interval. In contrast, LIF in a concentration-dependent and time-dependent manner decreased basal and ACTH-stimulated adrenal androgen release from dispersed cells isolated from the bovine adrenal zona reticularis. Because LIF release increases during inflammatory stress and this cytokine stimulates adrenal cortisol release and inhibits adrenal androgen release, this cytokine may play an important role in regulating the release of adrenal steroids during inflammatory stress.     

Insecticidal and fungicidal activity of new synthesized chitosan derivatives

Chitosan, the N-deacetylated derivative of chitin, is a potential biopolysaccharide owing to its specific structure and properties. In this paper, we report on the synthesis of 24 new chitosan derivatives, N-alkyl chitosans (NAC) and N-benzyl chitosans (NBC), that are soluble in dilute aqueous acetic acid. The different derivatives were synthesized by reductive amination and analyzed by 1H NMR spectroscopy. A high degree of substitution (DS) was obtained with N-(butyl)chitosan (DS 0.36) at a 1:1 mole ratio for NAC derivatives and N-(2,4-dichlorobenzyl)chitosan (DS 0.52) for NBC derivatives. Their insecticidal and fungicidal activities were tested against larvae of the cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), the grey mould Botrytis cinerea Pers (Leotiales: Sclerotiniaceae) and the rice leaf blast Pyricularia grisea Cavara (Teleomorph: Magnaporthe grisea (Hebert) Barr). The oral feeding bioassay indicated that all the derivatives had significant insecticidal activity at 5 g kg(-1) in artificial diet. The most active was N-(2-chloro-6-fluorobenzyl)chitosan, which caused 100% mortality at 0.625 g kg(-1), with an estimated LC50 of 0.32 g kg(-1). Treated larvae ceased feeding after 2-3 days; the mechanism of action remains unknown. In a radial hyphal growth bioassay with both plant pathogens, all derivatives showed a higher fungicidal action than chitosan. N-Dodecylchitosan, N-(p-isopropylbenzyl)chitosan and N-(2,6-dichlorobenzyl)chitosan were the most active against B cinerea, with EC50 values of 0.57, 0.57 and 0.52 g litre(-1), respectively. Against P grisea, N-(m-nitrobenzyl)chitosan was the most active, with 77% inhibition at 5 g litre(-1). The effect of different substitutions is discussed in relation to insecticidal and fungicidal activity.     

Biological, serological, and molecular variability suggest three distinct polerovirus species infecting beet or rape

Yellowing diseases of sugar beet can be caused by a range of strains classified as Beet mild yellowing virus (BMYV) or Beet western yellows virus (BWYV), both belonging to the genus Polerovirus of the family Luteoviridae. Host range, genomic, and serological studies have shown that isolates of these viruses can be grouped into three distinct species. Within these species, the coat protein amino acid sequences are highly conserved (more than 90% homology), whereas the P0 sequences (open reading frame, ORF 0) are variable (about 30% homology). Based on these results, we propose a new classification of BMYV and BWYV into three distinct species. Two of these species are presented for the first time and are not yet recognized by the International Committee on Taxonomy of Viruses. The first species, BMYV, infects sugar beet and Capsella bursa-pastoris. The second species, Brassica yellowing virus, does not infect beet, but infects a large number of plants belonging to the genus Brassica within the family Brassicaceae. The third species, Beet chlorosis virus, infects beet and Chenopodium capitatum, but not Capsella bursa-pastoris.